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Dutch924-racer
Joined: 23 Jul 2007 Posts: 1077 Location: The Netherlands
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Posted: Mon May 15, 2017 4:15 am Post subject: Need help with 931 engine problems |
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I have a/ some problems with the 931 series 2
When cold: running rough at idle/ low rpm
When warm:
Running nicely, great power
But running lean at cruise(AFR 17-20) and under boost (+/- 14)
Vacuum reading is 13/14 – the vacuum gauge says problem with timing
I checked the timing with a stoboscoop and I can see the ‘dot’ on the flywheel which seems to be good.
The enige is fully rebuild.
Modifications:
951 turbo s and intercooler
Stage 1 camshaft
Forge boost controller
Forge recirculation valve
937 DITC
What direction should I be looking for ? _________________ 937 trackday car
Series 2 engine
951S turbo and intercooler
Fast road camshaft
Forge recirculation valve + boost controller |
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924-76
Joined: 05 Jun 2006 Posts: 1475 Location: Ontario, Canada
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Posted: Mon May 15, 2017 4:25 am Post subject: |
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Have you perform a smoke test for vacuum leak?
What is your AFR at idle?
Vacuum gauge should read around 17 at idle. _________________ 1976 924 N/A ROW SOLD
1980 931S
1981 931 Part car RIP |
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gegge
Joined: 27 Jul 2007 Posts: 1124 Location: Sweden
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Posted: Mon May 15, 2017 4:39 am Post subject: |
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Check CIS pressures, guessing the WUR. _________________ Carl Fredrik Torkildsen
924 turbo -81 Carrera GT RESTOMOD
924 turbo -80 Dolomite De Luxe
924 -85 DP kit, BBS RS, M030 and tuned engine
924s -86 Black on black turbo with Fuchs |
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morghen
Joined: 21 Jan 2005 Posts: 8880 Location: Romania
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Posted: Mon May 15, 2017 4:46 am Post subject: |
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WUR
Check the CIS pressures.
Check if injectors are working right.
Check if fuel pump is getting 20 Amps. _________________ https://www.the924.com |
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Dutch924-racer
Joined: 23 Jul 2007 Posts: 1077 Location: The Netherlands
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Posted: Mon May 15, 2017 4:47 am Post subject: |
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AFR at idle is 14.5-15.
I haven't checked the fuel pressure yet. Will do that next week.
Injectors are new
What do you mean with check the fuel pump is getting 20amp ? _________________ 937 trackday car
Series 2 engine
951S turbo and intercooler
Fast road camshaft
Forge recirculation valve + boost controller |
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Dutch924-racer
Joined: 23 Jul 2007 Posts: 1077 Location: The Netherlands
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Posted: Mon May 15, 2017 5:21 am Post subject: |
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just pulled out the spark plugs, the all look black, so they don't look like it is runnign lean _________________ 937 trackday car
Series 2 engine
951S turbo and intercooler
Fast road camshaft
Forge recirculation valve + boost controller |
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Carrera RSR
Joined: 08 Jan 2010 Posts: 2309 Location: Somerset, UK
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Posted: Mon May 15, 2017 5:47 am Post subject: |
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Can you swap out the AFR sensor and gauge to rule out readout error? _________________ 1980 931 - forged pistons, Piper cam, K27/26 3257 6.10 hybrid turbo, 951 FMIC, custom intake, Mittelmotor dizzy & cam pulley, H&S exhaust, GAZ Gold, Fuch'ed, Quaife
Now www.924board.org/viewtopic.php?t=34690
Then www.924board.org/viewtopic.php?t=31252 |
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morghen
Joined: 21 Jan 2005 Posts: 8880 Location: Romania
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Posted: Mon May 15, 2017 5:58 am Post subject: |
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recalibrate your wideband sensor and gauge. _________________ https://www.the924.com |
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Dutch924-racer
Joined: 23 Jul 2007 Posts: 1077 Location: The Netherlands
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Posted: Mon Jun 05, 2017 5:49 am Post subject: |
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Checked the fuel pressure today with a running engine:
Pump pressure: 6,2 bar (should be between 5,8-6,5) ok
Cold pressure: 1,5 bar (should be between 2,4- 2,8 ) not ok
Warm pressure: 2.0 bar (should be between 3,45-3,85) not ok
Does this means my WUR has not died ?? I haven't checked if it gets 12v yet.
_________________ 937 trackday car
Series 2 engine
951S turbo and intercooler
Fast road camshaft
Forge recirculation valve + boost controller |
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Back to top |
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Dutch924-racer
Joined: 23 Jul 2007 Posts: 1077 Location: The Netherlands
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Posted: Sat Jul 01, 2017 1:28 am Post subject: |
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problem solved, the wur was bad, replaced it and all pressures are good now.
AFR is also good at cruise now _________________ 937 trackday car
Series 2 engine
951S turbo and intercooler
Fast road camshaft
Forge recirculation valve + boost controller |
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Back to top |
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